In This Article:
Liquid tar is poured on badly decayed asphalt roof shingles and spread around with an old corn broom.
About 1 Hour
Bruce W. Maki, Editor
This article describes a simple way to temporarily patch a leaking roof by applying liquid roofing tar to old worn-out roof shingles. This patch won't last long (maybe 6 months) and I can't say I recommend doing this, but it worked for me. I replaced the shingles the following summer and I found no water damage from leaky shingles.
Working on a roof can be dangerous. Read Tips On Not Dying from an earlier roofing article.
From the ground these shingles didn't look too bad, but from up on the roof it was obvious that these shingles need replacing.
This garage is 28 years old, and I'm sure that the shingles have never been replaced.
These are absolutely the worst, most deteriorated shingles I've ever seen, and I'm ashamed to say that I own them.
This gray spot is roofing cement (from a caulk tube) that I applied about one year ago to try to stop a minor roof leak.
I had applied roofing cement to a couple dozen possible weak spots. It seemed to help because water stopped dripping onto my workbench, but I could still see wetness on the underside of the plywood where it met one of the roof trusses.
I knew the shingles on my garage were bad when I bought this house a year earlier. But I had plenty of other projects and distractions that prevented me from starting the fairly easy job of replacing the shingles.
With warm weather all but gone for the year I decided to investigate a temporary roofing repair that would last until spring and stop the minor roof leak. My plan was to tear off the shingles and install one of the new synthetic shingle underlayment products that are capable of withstanding the elements for six months or more. This project would involve removing the old shingles, hauling them away and installing the new underlayment to the roof sheathing. This would require a day or two of dry weather, certainly possible in Northern Michigan in mid-November.
But then I decided to take an even easier approach and just try a quick-and-dirty roof patch method: applying tar to the most-deteriorated shingles in the area of the leak. This repair cost 20 bucks and took about an hour including time to clean the tar-covered tools.
Using a push broom, I first swept the leaves and tree branches from the roof. Then I dragged an air hose up to the roof and used an air nozzle to blow the remaining debris from the areas to be patched. There was a lot of junk in the spaces between the shingle tabs and I knew that I needed to remove this debris or the tar might not adhere properly.
I figure that a leaf blower would also blow off the debris if compressed air was not available.
The tar is DeWitt's Wet-Stick Roof and Foundation Coating, which I bought at Home Depot for $6.47 a gallon.
The small trowel on the left is a mason's brick trowel. This tool is good for scraping the last bit of tar from the can.
The charcoal starter fluid is a convenient solvent for cleaning tar that got on the wrong places.
The main tool: An old corn broom.
I trimmed off the ends of the bristles because... I just had a hunch that it would work better with shorter and stiffer bristles.
I poured the tar from the can...
...and spread it around with the broom.
I found that it's important to brush the tar downhill as much as possible, to prevent the shingle tabs from tearing. I was able to carefully brush in a sideways motion as long as I watched to make sure I wasn't lifting up the shingles.
The first can covered about 8 square feet.
I turned the can upside down to let the residual tar drip out. Then I used the brick trowel to scrape the remaining tar from the can, wiping the trowel on the broom.
Three gallons of tar covered about 30 square feet.
It took me about 20 minutes to apply this tar.
This tar product is fairly thin and runny. The tar poured easily from the can, and I'm sure the tar would eventually run all the way to the edge of the roof if I didn't spread it around right away. To keep the material warm I kept the cans of tar inside the house before using them. This tar seemed to get thicker as it cooled down in the 45-degree outdoor temperature.
Note the difference between plastic roof cement and this roof and foundation coating. Roof cement is very thick and requires considerable effort to scoop it from the can. Roof cement may be useful for some areas where a thick layer is needed, but it is difficult to spread around in a thin layer. Roof cement can be miserable to use when cold because it gets quite stiff. On a hot day roof cement flows pretty easily.
The next day I took a close-up picture of this repair job. The tar was still tacky but I could tell that many of the potential leak spots had been covered by the coating of tar.
I suppose a second coat of tar could be applied if the first coat had not covered some spots. Maybe just using a small paint brush to apply tar on problem areas would work.
Before you hurt yourself, read our disclaimer.
A lot of people would just throw away this broom because cleaning up sticky tar can be such a hassle. I don't fault anyone for discarding a cheap tool like this, but tar-covered tools can be cleaned up with just a little effort.
I put the broom and trowel in an empty 5-gallon drywall mud bucket. Then I poured in almost a gallon of used mineral spirits.
After using mineral spirits to clean paint brushes or greasy auto parts, I just pour the liquid into an empty paint thinner jug that is clearly marked as "used". The solid particles settle to the bottom leaving reasonably clear mineral spirits on top. This jug of used mineral spirits looks black because I recently used it to clean up the same broom for another roof patch job.
After rinsing the broom and trowel with dirty-looking used mineral spirits, I rinsed them again using about half a quart of clean mineral spirits. To shake the liquid from the bristles I just held the broom handle between the palms of my hands and rubbed my hands back-and-forth to spin the broom and fling out the excess liquid. Of course, I did this over the drywall bucket.
Many years ago a chemist explained to me that charcoal starter fluid is simply mineral spirits (paint thinner) that has been run through an activated charcoal filter to remove the odor-causing chemicals. Odorless mineral spirits is often sold alongside regular mineral spirits, for a higher price. For many years I have kept a couple of cans of charcoal starter fluid on hand, simply as a convenient package of paint thinner. I've been buying the stuff when I shop for groceries at Save-A-Lot, which has the lowest price I've seen.
The patch has a shiny black appearance, which is kinda ugly. This shine will become dull in a few months as sunlight starts to degrade the tar. Eventually the tar will turn a dull gray color, since bituminous asphalt cannot tolerate the ultraviolet light in sunlight.
Consequently this patch is temporary. I will be surprised if this tar doesn't become badly cracked within six months.
UPDATE: Almost a year after I patched this roof, I tore off the old shingles and replaced them. During the winter and spring before replacing the roof, I found no leaks in the roof, so the patch worked. Actually, the tar held up surprisingly well.
A cheap tar patch like this WILL NOT LAST VERY LONG. The lifespan depends on the amount of sunlight received by the tar.
This patch survived until the following spring because the sunlight isn't very strong in the winter, and the roof was covered by snow for much of the winter.
I have seen unprotected tar patch jobs survive for a couple of years if the patch did not receive much direct sunlight. I've heard that bituminous asphalt (which includes roofing tar) will last about 6 months when fully exposed to sunlight. Consequently asphalt is always covered with something durable.
For example, until a couple of decades ago flat roofs were routinely made from several layers of tar paper bonded with hot-mopped asphalt tar. The asphalt was covered with a layer of gravel to protect the asphalt from sunlight. This process has been seen on Discovery Channel's show Dirty Jobs.
Ordinary roof shingles are made from asphalt-impregnated paper (now with fiberglass reinforcement) that is covered with fine granules of colored stone. The granules eventually fall off, leaving the asphalt exposed to sunlight. Any abrasion on asphalt shingles, such as walking on them or scraping snow from the roof, will cause more granules to fall off, which will accelerate the deterioration.